I cannot import or export anything in Blender. It throws
Blender is definately running its own version of python, which is python 3.
You get that error message because your "Blender Python" is trying to import reprlib and it should find that file in the Blender python directory, which in your case is "F:\Steam\steamapps\common\Blender\2.79\python\lib\reprlib.py". Make sure this file exists.

For some reason your Blender Python doesn't find that file and looks elsewhere. You might have misconfigured your Scripts directory in Blender. Check you preferences, they should look like this:


Uninstalling and reinstalling probably didn't help because the preferences will not be deleted as they are stored in you application data directory.

If that's not the problem, then there is probably something wrong with your environment variables for python. Check your environment variables as described in this link:
https://www.katsbits.com/tutorials/blender/pythonpath.php